Electrically responsive fluid logic system and method of assembly



137-013 XR 3548857 SR I United States Patent n113,548,857

[72] Inventors Lewis G. Anderson 2,802,918 8/1957 Boyle 200/152.9X Columbus, Ohio; 2,901,580 8/1959 Kelley 200/ 152.9 David J. Thomson, Summit, NJ. 3,271,543 9/ l 966 Schonfeld et al. ZOO/81.6 [2!] Appl. No. 659,698 3,422,259 1/1969 Freeman 235/201 [2 1 Filed s- 10, 1967 OTHER REFERENCES 1 Patented Truslove, D. J., Pneumatic Diode, in IBM. Technical Dis- Asslgnee 1 3:" li mrg gxx g s closure Bulletin, Vol. 6 No. 3, August 1963, p,30.

urra a a col-Damion f New York Primary Examiner-William R. Cline Attorneys-R. J. Guenther and Edwin B. Cave [54] ELECT RICALLY RESPONSIVE FLUID LOGIC SYSTEM AND METHOD OF ASSEMBLY 20 Claims, 7 Drawing Figs.

[52] U.S. Cl 137/251, S C A gas flo i a miniaturized fl id logic circuit is 137/13. 137/815: 251/129: 29/ 157- 235/201 switched electrically by conducting gas flow into and out of [51] hit. 3/06, the same end of an elongated chamber that holds a mercury F 15 5/0 F 16k ball which is movable from a flow-obstructing to a flow-releasposition and selectively moving the the of 251, l3;25l/l29, 141,65; both a constant magnetic field established across the balls -6, 29/1571, q track and a varying current applied to the ball through contacts on the chamber walls. The action is made monostable by References Cited constricting the chamber to distort the ba ll in o ne of its posi- UNITED S T PATENTS tions. The distortion forces the ball back to the other posi- 2,312,672 3/l 943 Pollard, Jr. 200/ 152.9X tion when no current flows.

ELECTRIC PLLSE SOURCE PATENTEU M222 lam SHEET 1 UF 4 FIG.

$ 15 an d:

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51.5 C 7' R/C PULSE SOURCE 0 FIG. 4

GAS OUT 5,45 0 70 LOG/C 7'0 LOG/C T r PL PT TPL CB TA RIC/4L PUL SE SOURCE P5 PATENTED UEC22 I978 SHEET H [1F 4 FIG. 5

ELECTRICALLY RESPONSIVE FLUID LOGIC SYSTEM AND METHOD. OF ASSEMBLY CROSS REFERENCE TO RELATED APPLICATIONS This invention is. related to that disclosed in the applications of H. Winter, Ser. No; 659,686, filed Aug. 10, 1967 and D. J.

Johnson, Ser. No. 659,794, filed Aug. 10, l967,both being filed concurrently herewith, and both being assigned to the same assignee as this invention.

BACKGROUND OF THE INVENTION This'invention-relates to transducing electrical logic information into fluid'logic informatiomparticularly for fluidically actuating the connections at the crosspoints of arrays, or socalledswitch blocks, that in stages selectively connect telephone subscribers to truck lines in telephone-switching system.

Telephone central office-switching systems have in the past .2 utilized electromagnetsbotli forestablishing connections and furnishing the information or logic bywhich the connections are selected. Such systems are slow and bulky. In newer *systems electronically-developedcontrol currents actuate electromagnets which-open and close comparatively small relay contacts called ferreeds. When closed, these ferreeds interconnect electronically selected crosspoints between transverse sets of otherwise unconnected parallel coordinate conxductors-which form arrays. Successive arrays, or switch blocks, of this type then selectively connect an incoming or outgoing call to an incoming or outgoing trunk. However, reliable ferreeds are difficult to manufacture and require bulky envelopes and electromagnets.

Consideration has been given to connecting the-crosspoints with semiconductor switches. However, nomatter how effective these switches, each of them introduces an undesirable :1 impedance. at the crosspoints. Thus, if the number of arrays,

and hence the number of crosspoints through which an incoming signal must pass from one telephone subscriber to another is great, considerable distortion and loss of signal is experienced.

The copending application of-H. Winter Ser. No. 659,686,

J filed Aug. 10, 1967 being concurrently "filed herewith and assigned -to the same assignee; of this application, eliminates many. of these difficulties byfiuidically actuating mercury ;balls that establish contact between the coordinate conductors or crosswires in arrays at the crosspoints without introducing .:additional'resistances. The low-resistance contact affordable li by such-mercury balls between two metallic coordinate con- ".fductors is eminently-suitable for such work. Moreover, the

'ispeed'with whichthe fluid can actuate such mercury balls is more than adequate. However, the operation of such-systems still depends upon. actuating the fluid which moves the ball .contacts-with electrical input pulses. In the past, reasonably L' fast conversions from'electrical pulses-to fluid pulses have been difficult to obtain. Available solenoid-actuated fluid'pulsers have been found'far'too bulky and expensive to use as .'electric-to-gas transducers, especially when compared to the compact fluid-actuated-switching' arrays described in thebeforementioned application of H. Winter.

' SUMMARY OF THE INVENTION Accordingto a feature of the invention these deficiencies of tracks, also applying the electrical input signal currents "through the respective balls by means 'of suitable contacts entering the chamberf'The electric and magnetic fields then move the balls along'thechambersand switch the fluid flows z.accordingly. Each chamberyits contacts, ports and magnets ":Lthus form a separate transducer.

According to another feature of the invention the switching "operation of the resulting transducers is made monostable by center layer to form chambers which register with grooves and ports initheouter-layers, and applying magnets so that suitable mercury ,ballsinserted in the chambers'can be moved by the magnets-and contacts. I

According to anotherfeature of the invention the magnetic fields areapplied to each chamber in an array by forming on either side of the chambers in the center insulating layer, strips of elongated insulating magnetic material such as ceramic ferrite. The ferrite strips extend between rows of chambers. By virtue of this construction large numbers of such switches may be batch-manufacturedand suitable connections and gas pressures applied.

These and other features of the invention are pointed out in, the claims. Other objects and advantages of the invention will become better understood from the followingdetailed description when read in lightof the accompanying drawings.

BRIEF DESCRIPTION 'OF THE- DRAWINGS In the drawings: FIG. lis an explodedperspective block diagram-partially in schematic form of axtelephone switching grid or system suita- DESCRIPTION OF PREFERRED EMBODIMENT In the telephone-switching system of FIGS. 1 and 2 eight input'lines lll arrive from individual telephone circuits. They terminate ineight parallel "input :coordinate conductors or coordinates IC printed; plated, or vapor deposited between the-lower and upper surfaces'of an array board B01. With seven. similar. boards B02 to B07 at the end of lines ILZto IL7,:the boardiBO1 forms acoordinate input block .13 in. a switching-system such. as described in the beforementioned copending application of H. Winter Ser. No. 659,686, filed Aug. 10, 1967 filed concurrently'--herewith. Thelines'ILI to [L8 and boards-B01 toBOS are referred to generallyas'lines IL .and boards BO. Eight lineslL terminate in input coor- .dinates IC in each'of the eight boards BO. This furnishes a total of sixty-'fourinput'lines II... On each of the eight boards BO eight output coordinate conductors or coordinates OC. alsotbetween the bottom and top surfaces of the board BO but not contacting the input coordinates IC, terminate in link wiring LW'. The latter-:connectsthe output coordinates 0C, which arev transverse to the inputcoordinat'es, to input coordinates The switches at the crosspoints CP are energized by transducers in an input interface IF, through an intermediate gaslogic circuit GLC. The latter is pressurized by the pump P through a duct D. The duct D also forms a pressure path to the input interface If that includes the transducers. The interface operates between the gas-logic circuit GLC and six input binary lines IBL from an electric computing pulse source PS. The pulsed lines IBL select which crosspoint on which board B is to be closed in the input block IB. Six output binary lines OBL forming an output address OA and entering the interface IF from the source PS select on a binary basis which crosspoint on which board OB is to be switched in the block OB. The gaslogic circuit actuates the switches at the crosspoints on the basis of the selections of the binary lines.

FIG. 2 illustrates that the selection of one crosspoint CP in the input block IB and one crosspoint CP in the output block OB uniquely connects one input line IL to one output line OL. For example, closing the switch at the crosspoint marked with a circle, at the bottom left of FIG. 2, and closing the crosspoint in the middle right of FIG. 2 shown by a circle, connects one particular input line IBL to one selected output line OBL. On a binary basis three of the input binary lines IBL of the input address select the board B0 of block IB onwh ich the crosspoint is to be closed and the other three input binary lines IBL select which input coordinate IC the switch to be closed on the selected board will effect. Of the output binary lines OBL three lines select a board on the output block OB. Simultaneously, these selections serve to choose an output coordinate OC in the board B0 on the input block 18 as well as an input coordinate IC on the selected board of the output block. The remaining three output binary lines OBL select the coordinate of the board B0 on the block OB and thus the desired output line. This connection process is similar to that used for connecting magnetic array switches. For example, the so-called No. crossbar system for telephone lines operates on the principle.

In FIGS. 1 and 2 the switches at crosspoints CP constitute mercury balls encapsulated in suitable chambers each located so that an input coordinate IC and one output coordinate OC passes through the chambers at each crossover point. The chambers and the mercury balls are arranged so that gas flowing through suitable ports to the chambers pneumatically move the mercury balls into or out of contact with each of the crossbars in the input blocks and output blocks. By virtue of the immediate contact between the crossbars through the mercury balls, low ohmic connections are established between the desired input and output lines. Such pneumatic-switching systems may be manufactured cheaply by batch-processing and are extremely reliable. The workmanship and labor required to accomplish this is much less than that required for comparable magnetic or electromagnetic-switching systems.

To utilize the advantages of the pneumatic-switching system the electrical input signals are transduced into suitable pneumatic signals by constructing the interface IF from a number of transducers as illustrated schematically in FIG. 3. Here, a mercury ball MB rests in a horizontal chamber CB of a ceramic body B whose portions PN bounding the ends of the elongated chamber are magnetically neutral. The bodys portions N and S bounding the elongated walls of the chamber CB are composed of insulating magnetic ferrites to form north and south poles. The main gas flow enters from the pump P through the duct D through a port PT. The latter ends at one end of the chamber CB in a porous plug'PL. A second porous plug PL also at the same end of the chamber CB forms the start of an outlet port OPT which leads to the gas-logic circuit GLC. When the pulse source PS furnishes a pulse, conductors C01 and CO2, shown schematically as lines, and extending respectively through the under and over side of the mercury ball MB, pass a current vertically through the ball MB. The horizontal magnetic field formed by the poles on the elongated sidewalls of the chamber CB combines with the current to move the ball along the chamber CB until it unblocks the path between ports PT and OPT. This movement of the mercury ball releases the pressurized gas from the pump P. The gas flows to the gas-logic circuit GLC during the period of the electric pulse. A dump port DP having a ceramic porous plug releases to the atmosphere gas forced by entry of the ball MB from the now-occupied portion of the chamber.

In the quiescent position shown the input port PT communicates directly with the dump port DP so as to avoid forcing the ball MB in the direction of the dump port. The output port OPT is, however, covered by the ball MB. The port PT must still be close enough to the end of the chamber CB to allow the ball MB to clear both ports PT and OPT.

The chamber CB is constricted at one end to distort the ball MB as it is moved electromagnetically to that end. The distortion creates surface tension forces which constrain the ball to return to its initial position between the ports PT and OPT when the current therethrough ends. This again closes the path of gas from the pump P to the gas logic circuit GLC and produces a pulse of gas pressure corresponding to the electrical pulse from the source PS.

All the members into which the mercury ball comes in contact are composed of materials not wettable by mercury. The contacts CO1 and CO2 preferably consist of platinum or stainless steel on the upper and lower surfaces of the chamber walls.

Other details of the structure of the interface IF appear in FIGS. 4 to 7. FIG. 4 is a cross section of the interface IF. A plurality of chambers CB corresponding to those shown in FIG. 3 are formed by cutting or punching holes in a center ceramic layer CL2 of three ceramic layers'CLl, CL2 and CL3 whose plan views appear in FIGS. 5, 6 and 7. The holes CH have the pear shapes shown in FIG. 3 and in the plan view of FIG. 6. Completing the upper and lower walls of the chamber CB are platinum tabs TA vapor-deposited, plated, or otherwise deposited on the upper surface of a ceramic layer CL! and the lower surface of a ceramic layer CL3. A copper bar connector CU imbedded in the lower ceramic layers CLI under an edge of each of the tabs TA connects the tabs to each other and to the edge of the layer where it may be grounded. The platinum material between the copper bar connector CU and the interior of the chamber furnishes the mercury ball MB with a surface which it cannot wet. The vertical chamber walls made of the ceramic material are also not wettable by the mercury material.

Furnishing the electrical pulses for conduction through each of the mercury balls on a selective basis are a plurality of conductors CO contacting the tabs TA on the lower surface of the upper ceramic layer CL3 and leading independently to the edge of the interface. There they connect to the lines IBL and OBL and to the electric pulse source PS in FIG. 1. The tabs TA and the connectors CU as well as the conductors C0 correspond together to the schematically-illustrated conductors CO1 and CO2 of FIG. 3. A groove GR on the upper surface of the lower ceramic layer CLl serves to lead pressurized gas from the pump P to the input or entrance ports PT of the individual chambers. These ports PT extend directly into the chambers CB although theyare plugged by the porous plugs PL. The port PT in each case may be drilled or punched in the ceramic layer CL2. The gas output to the logic circuit GLC passes through the ports OPT punched in the layer CL2 and plugged with a porous plug PL at the edge of each chamber. The output port OPT continues through suitable openings also designated OPT punched in the upper ceramic layer CL3 that lead the intermittently obstructed gas flow to the logic circuit GLC of FIG. 1. A dump groove DG terminates at a porous plug PL at the smaller end of the chamber CI-I. It releases gas displaced by the mercury ball when the latter enters the smaller end of the chamber CH. The positions of the individual ports PT and OPT correspond to those shown in FIG. 3.

The magnetic field furnished by the N and S regions in FIG. 3 are formed in the layers CL2 by making the sections marked S and N from properly magnetized ceramic material and making the section marked PN from magnetically neutral material.

This can be accomplished-by; collecting portions of premagnetized layer material and! bonding them together or by a process ofproperly'magnetizing the material after it is heatformed such as is done with magnetic tape.

As a result of the'vertically traveling current from the pulse source PS passihg through the mercury ball MB, and of the horizontal field establishedmagnetically by the ceramic magnets, a horizontalforce produces a motion of the mercury ball into the narrower end of the chamber CB in, each of the switches of FIGS. 4 through 7. The pulse source remains in electrical contact with the mercury ball throughout its travel length. Thus since the-field remains substantially the same throughout the travel length of the mercury ball, the horizon- .Ital forces remain appliedto the ball until the pulse-ends. Then the distortion constrained upon the ball by virtue of the constriction in the chamber CB at theiend to which the ball has been forced causes the ball to return to its initial position. In its constrained position the ball releases flow of gas from the input port PT- to the output'port-OPT. in its returned position flbwof gas at the output port OPT iscut off 'because the. ball obstructs flow there. In this way an electrical pulse is transduced into a pneumatic, or gas, pulse for the gas-logic circuit GLC.

The structures of FIGS. 4 to 7 may be batch-fabricated. This is accomplished by separately forming each of the layers in a ceramic press. The center layer CLZ may be formed by first fabricating the elongated shapesrepresented by the portionsS and N and'inserting therein the portions represented by PN. At first the chamber Cl-lcan be ignored. Onthe other hand, suitable results are available by forming a singleceramic layer GL2 directly and magnetizing. it in the heating process or thereafter. inlayers CLl and CL3 the conductors CO'and connectors CU- may be imbedded by, printed circuit.

techniques. Grooves GR, D6 and the. groove forcarrying-the conductors CO and connectors CU are formed in the'pressing process. Suitable holesfor'the ports PT andOPT and chambersiCHare'punched into the ceramic layers and the tabs TA vapor-deposited, plated, or otherwise deposited in suitable locations. The process is completed by overlying the layers CLl and (12 bonding them under pressure, adding the mercury balls MB and then bonding the. layer CL3 to the top of the layer CL2 under'pressure.

' The illustrated embodiments of the invention show the structure to be'used with an 8 X 8grid matrix. However, larger matrices are possible. Moreover, the layers may be manufactured in huge sheets having'thousands-of matricesand then cut as necessary. As a result extremely simple manufacturing operations'can furnishmultiplicities of switching-elements for gas logic. This is possible because there exist considerable tolerances in the location of the input and output ports. The sizes of the input and output ports may also vary considerably and may be made any size suitable for theoperating speed.

The directionof movement of eachmercury ball MB neednot necessarily be horizontal. By placing the tabs TA along the vertical sides of a vertically-elongated chamber so that current can-be applied horizontally althoughfltransverse to the magnetic field, a ball maybe made to move vertically. Monostable condition can be achieved by again restricting the upper end of the chamber so asto distort the ball or simply by allowing the effect of gravity to force it down in the-absence of a'magnetic field'and electric current.

While embodiments ofthe invention have been described in detail, it will be obvious to those skilled in the art that the-invention may be practiced otherwise without departing from its spirit and scope.

We claim:

l.'A- transducer for translatingelectrical signals to fluid flow signals comprising material means for. forming an elongated chamber,-said material means forming fluid ports to and from said chamber, metal means in the chamber having a. liquid character and capable of forming a ball. movable along said chamber between a position obstructing the ports and one releasing fluid flow through" the ports, magnetic means for forming afield transversetothelength of said chamber, .conductive'means for contactingqthe ball throughout its travel along said" chamber and forapplying a current through said 2. A transducer as in claim 1 wherein said material means form a dump port entering said chamber at one end for releasing fluid moved by moving said; metal means.

3. vA transducer as in claim 1 wherein said metal means comprises-a mercury ball.

4. .Atransducerasainrclairn 1 wherein said material means. and said. conductive means contact said metal means only with:

materialsnot wettable bysaid metal means.

5 A t'ransducer as inclaim 1 wherein said magnetic means form a portion of saidmaterial means.

6. A transducerasinclaim 1 wherein said chamber is narrower at one end "than the-other so as to distort said metal means'when'said metalmeans moves into said narrower end and thereby force said metalmeans back into said wider end when no electromagneticforce is applied to said metal means.

7. .A=transducer as'in; claim 1 wherein said material means comprise threezstacked and interbonded ceramic layers, said magnetic means forming ,a portion of the centerone of said layers.

8I.An*interface for an electrical input to a fluid control system comprising insulatingblock means, a plurality of elongated chambers formed-insaid block means, magneticmeans. in said blockmeans for establishing respective magnetic fields acrossthe length of each of said chambers, said block means forming aplurality of;gas..ports. to bepressurized atone end and terminating at aportion of'said block means so as .to form gasport outputs, saidlportsseach passing throughan end of respectiveones ofsaidzch'ambers, liquid conductor means in said chambers having a convex meniscus relative to the materialsof the walls..of.said.chambers so as to form-a ballwhich-doesnotiwetsaidwalls. said liquid conductor means being movable alongsaid :chambers from positions obstructing gas flow through said' ports. to positions permitting flowthroughsaid ports, and conductive means extending through said block means andalong- -respective. lengths of said chambers for applying to said liquid'conductor means input signal. currents transverse to the direction of said field and transverse to the-lengths of said chambers,.whereby signals applied to respective ones ofsaidiconductive means moves said ball means between'obstructing and. nonobstructing positions in said chambers relative to saidzports.

9. An interface as in claim'8wherein said chambers are narrower in one end than-the other so as to bias said ball'means toward the widerend.

10; An interface asin claim 8 wherein gas lines communicating-with one end ofsaid chambers releases gas caused by motion .of said balllmeans.

ll. Aninterface as.in claim 8, wherein said block means include three stacked and interbonded insulating layers, the center one of said layers having a plurality of openings; punched through to formthe-chambers, said center. layer hav--- ing continuous stripsof magneticmaterial bordering on said; chambers.

12. An interface as in claim 11 wherein said conductive: means'include. tab. means on the inner surfaces ofsaidlouter; layers extending into the 'chambersfor contacting said ball means-together with current-carryingmeans embedded in the;

inner surfaces of' the outer layers and connecting; said tab":

means to theedge of saidblock means.

13. An interface as in claim 11 wherein said layers include: grooves and open portions in registration for formingsaid port: means.

l4. Aninterface as in claim 11. wherein saidballmeans-are. composed of mercury, saidbloclcmeans of ceramic and said: tab means of platinum.

15. A fluid control system comprising fluid logic means, electrical means for responding to said fluid logic means, insulating block means, a plurality of elongated chambers formed in said block means, magnetic means in said block means for establishing respective magnetic fields across the length of each of said chambers, said block means forming a plurality of gas ports, gas pressure means connected to said ports for inducing flow therein, said gas ports terminating ata portion of said block means so as to form gas port outputs, said ports each passing through an end of respective ones of said chambers, liquid conductor means in said chambers forming a convex meniscus relative to the materials of the walls of said chambers so as to form a ball which does not wet said walls, said liquid conductor means being movable along said chambers from positions obstructing gas flow through said ports to positions permitting flow through said ports, conductive means extending through said block meansand along respective lengths of said chambers, electrical input means connected to said conductive means for applying to said liquid conductor means input signal currents transverse to the direction of said field and transverse to the lengths of said chambers, whereby signals applied to respective ones of said conductive means moves said liquid conductor means between obstructing and nonobstructing positions in said chambers relative to said ports, said gas output ports communicating with said fluid logic circuit to form an input thereto.

16. A system as in claim 15 wherein said chambers are narrower in one end than the other so as to bias said ball means toward the wider end.

17. A system as in claim 15 wherein said conductive means include tab means on the inner surfaces of said outer layers extending into the chambers for contacting said ball means together with current-carrying means embedded in the inner surfaces of the outer layers and connecting said tab means to the edge of said block means.

18. The method of forming an interface between a fluid control system and an electrical input, which comprises forming two ceramic layers, forming a third ceramic layer having a plurality of magnetic fields established therein, forming openings and grooves in said ceramic layers so that respective openings and grooves register, when said third layer is placed between the other two-forming elongated chamber openings in the third of said layers transverse to said magnetic fields and to register with said grooves and openings, applying conductors to two of said layers so that said conductors terminate at said chambers, assembling one of said layers with said third layer, depositing liquid conductive balls into said chambers, assembling the remaining layer with said two layers, and bonding said layers together.

19. The method as in claim 18 wherein said step of forming the third ceramic layer comprises forming elongated magnetic members extending between a plurality of adjacent pairs of chambers, forming magnetically neutral portions and assembling and bonding said members and said portions.

20. The method as in claim 18 wherein said step of forming the third ceramic layer comprises assembling the constituents of said ceramic layer, magnetizing strips of said constituents while heating said constituents under pressure. 

